A THEORY FOR NONISOTHERMAL UNIMOLECULAR REACTION-RATES

A simple expression is derived for the survival probability of a react ive chemical species which is initially prepared at a temperature whic h differs from its surrounding. The competition between relaxation of reactants back to the external equilibrium and the possibility of reac tion may prevent the usual single exponential kinetics for the surviva l probability. The theory is accurate for activated reactions with mod erate (V double dagger/k(B)T greater than or equal to 3) to high reduc ed barrier heights. It is especially relevant for multidimensional sys tems where the characteristic energy at which a molecule dissociates i s greater than the barrier height. (C) 1997 American Institute of Phys ics.